David n



"citizen of the United States,

UNITED STATES:

PATENT ()FFICE.

DAVID M UARYALIIO ,oF- NEW YORK, ."N. Y.

- PAPER FOR BANK-NOTES, CHECKS, BONDS, STOCKS, AND OTHERlNSTRUMENlbS.

4 SPECIFICATION forming part of Letters'Patent No. 531,507,- dated December 25, 1s94. Applioatiom filed January 26, 1894. Seria.l 1i'o. 498,];3 01v (Np' pecimensJ To alt whom it may concern: 1 Be it known that I, DAVID N. OARVALHQfai York, in the county and State of New York, have invented certain new and use Im-v provementsin Paper-for l3ank-I\Totes, ears,

Bonds, Stocks, and other IllStlllmDl-SfOfi v Which-the following is a full, clear and exact duction of an improved safety paper for bank notes, checks, bonds, stocks and other instrudescription.

The subject of my improyements is pup-3 monts, of such nature that when airy cl emi- 09.1 or chemicals which will remove .iiik are iappliedthereto they will instantly and per-i1.

' I manently'discolor the paper, producing there;

" 'on a stain'wherever said chemical or chemicals-will havetouched it. a

obj e'et fof 'preparin g such papenis :to preventthe possibility ofaltering such documents. "It; is acommon practice withforgers to erase, bymeans of chemicals, the ink from portions of such documents; thus, in the case of cheeks, a portion of the amount maybe erased and a new amount greater thant h'at for which the check was drawn, may be sub-., stituted, or the name of the payee erased and 1 a'new'one substituted, oragain the name of the: indorseri or "indorsers changed {in like manner. Suchis R the ordinaryprocess of check raising. If on the application of the known ink-erasing agents, the ink'is erased, but at thesam'e time, a permanent and c'haracteristic stain is. producedjon the paper, the checkis, of course destroyed and the drawer or perso'nawhois to 'pay'the check is protected." The same applies to other documents where dishonest'peo'ple 'nptyde'sire to change them by .erasingthe'i'tikand .alterin gan y of the'parts or the-el tirety.

The paper of, my; ini'enti m is charged with an iodide, preferably solution of bismuth iodide inasolution of sodium iodide". Such. solution. is, readily byadding "to. an aqueous solutio'n of anyfbifsifiuthsalt, such as the chloride or: nit-rate, an exces's'of sodium iodideoreqfni'valentsalti'i v Thegbis'mutli iodide "mercury-ip'dide' (lIgIQ or (BiI thus'fo m ed in a precipitate and dissolves in, theeircess of sodium iodidepresenu Instead of'fibismuth ipdide, gljma'y. dissolve" iodide-of any .Q ii i other suitable-heai y metal, in sodium iodide,

1ny-object".being tQBobtaZi-n a solution ofi one of residing in Newx the ordinarilyinsol uble metallic iodides in s odiun io'dide,fin "other-alkaline iodide or known" equivalent} These double iodides have the eif'ee toffproduing, a more permanent staiiiwhen treated with an eraser. The

, paper'maybe charged with this solution either by'having itmixed with thejgaprjp'ulp in the course of manufacturaorthe surface of the paper may simply be spongedt herewith,

thejnethodofapplying it to the -paperbeing Imerely'a matterof technical detail. If such paper f'be treated with a ihypochloritai' espe cially after the addition'of an acid, which is .the regularer'asing process employed, the bismuth 'iodidesvill be discompos'ed a'n'diodine will beset free, staining tlie paper andformi g a stain which doesnotyieldto any" ordi ary reagents orsolven-ts. r

numberof coal It is-known thatit'hereare'a tar colors;,so called whichwgldrsyare also af- --fected by oxidizing re agpntsi -If such colors ne a p igiato paper theywill color "it, somethingthalt is desirable, and t'hey will'th-en naturally act also fa'sa' safe-guard, being themselves changed infc'olor byt'hedaypicalerasers. Ifthesolution of theseeolors be applied to my paper with the iodidesolution, a double protection is oifered besides the incidental adthe solution, moreoveiflbf thes'e dyes in water .before application,..1 findthat'the'addition to thezwater of sodiuinfiodide makes them disof bismuth'iodideijn sodium'iodidait may be,

" assumed to be the=double iodide of bismuth and -sodium (2NaI,TiI- The re-action which takes place by the act-ion on this come In regard to pound of anoxidizing .re-agent'in general terms, is the liberation of the iodine, and there [may also be effected-the formation of some definite compounds of iodine with the metals,

the stain produced being of a high degree ofperma'n'ency. q

. ids coloring matters suitable for my process,

'1 may cite as typical, primulin and benzidene colors in general. By the action of the oxidizing agents such as are used for erasing ink, these dyes have their colors changed and to their color change is superadded that due to the separation of the iodine.

Having thus fully described my invention, I claim as new and desire to secure by Letters latentv 1. A safety paper consisting of paper charged with bismuth iodide and sodium iodide, substantially as described.

2. As a new article of manufacture, the combination of paper and a salt of bismuth with iodide of sodium and either primulin, congo rod, or other pigment for the purpos of obtaininga variety of colors, substantially I 5 as described.

3. A check protecting fluid consisting of a solution of a benzidene dye with an alkaline iodide, substantially as specified.

In testimony that I claim the foregoing as 20 my own I sign this specification,in the'presence of two subscribing witnesses, this 19th day of January, 1894.

DAVID N. oimvAtuo.

Witnesses:

S. C. CAMPBELL,

SUMNER B. S'rILEs. 

